The fingertip clip-type pulse oximeter “PulsFit BO-800DX”, manufactured by Japan Precision Instruments, Inc., is known as a conventional example of this type of biological information measurement device (see Non-Patent Literature 1, for example). This fingertip clip-type pulse oximeter includes a sensor that detects a signal expressing a transdermal oxygen saturation level (SpO2) in arterial blood serving as biological information from a fingertip, which serves as a measurement area, and a display unit that displays the SpO2 value, in a main body that holds the fingertip. Dry cell batteries (two, size AAA) are installed in the main body as a power source.